單項(xiàng)選擇題在計(jì)算機(jī)網(wǎng)絡(luò)中,國際標(biāo)準(zhǔn)化組織(ISO)制定的開放系統(tǒng)互連(OSI)參考模型有七個層次。下列四個層次中最高的是()。

A.表示層
B.網(wǎng)絡(luò)層
C.會話層
D.物理層


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最新試題

翻譯:In these early days, as lamp oil, was the important product and the main objects of refining was to extract as much of it as possible from the crude. Lubricants and some fuel oil were also sold, but gasoline was burnt off as unwanted and bitumen was also largely useless.

題型:問答題

翻譯:A porous medium has a permeability of one darcy when a single phase fluid of one centipoise viscosity that completely fills the voids of the medium, will flow through it under conditions of viscous flow at a rate of one cubic centimeter per second per square centimeter cross sectional area under a pressure or equivalent hydraulic gradient of one atmosphere per centimeter.

題型:問答題

翻譯:A portion of the sample is used to determine the gravity of the oil expressed in AIP unit the lighter the oil, the higher the API gravity .In most cases the price paid for the coude is determined in prat by the API gravity, hence ,the importance of careful gravity determination in each instance.

題型:問答題

翻譯:The transportation of oil has also led to the spectacular development of gait ships ,the largest ships that ever sailed the oceans of the world .in the last few years ,since it has been necessary to ship oil from middle East-one of the largest oil producing regions-around the cap of Good Hope in south Africa these tanks has grown to almost unblievable proportions.

題型:問答題

翻譯:The total quantity of petroleum now thought to exist on Earth is about 14 trillion gallons. In weight that is only one-ninth as much as the total existing quantity of coal and ,at the present moment, petroleum is being used up much more quickly. At the present rate of used, the worlds supply of petroleum may last for only thirty years or so.

題型:問答題